Prior art designs of nozzle style refrigerant distributors for refrigeration and air-conditioning applications are well known. In a refrigeration system, the distributor is located downstream of the thermal expansion valve (TXV) and upstream of the evaporator. The purpose of the distributor is to evenly split the refrigerant fluid flow from the TXV into the many passages of a multi-circuited evaporator. The flow regime of the refrigerant flowing into the distributor is often a stratified two-phase (a layer of liquid and a layer of gas) fluid. This two-phase flow characteristic allows an uneven amount of gas and liquid to flow into the various circuits of the evaporator if a prior art manifold or header is used to split the flow.
The geometry of the prior art distributor ensures that the refrigerant flow is projected into a radially symmetrical cavity from which the feeder tubes (lines between the evaporator and distributor) emanate. Additionally, prior art distributors contain a plate (nozzle) with a thru-hole located in the center that increases the velocity of the stratified refrigerant flow. In this process, the pressure of the refrigerant fluid is decreased and the turbulent nature of the flow is increased. These effects are manifested in a more homogeneous (vs. stratified) flow regime that is more favorable for even distribution. However, these prior art designs rely on a correctly sized thru-hole (nozzle size) in the nozzle to be specified for each application. There are numerous variables that affect each application and the selection of the specific nozzle to be used. Some of these variables that influence the nozzle size selection are: the refrigerant type, the pressure of the evaporator, the level of subcooling of the refrigerant fluid entering the TXV, the evaporator temperature, the feeder tube diameter, the feeder tube length, etc. If the correct nozzle size is not installed into the distributor, the evaporator coil will demonstrate poor performance through either reduced capacity, system efficiency or a combination of both. A further obstacle with these style distributors is that the system must be “pumped down” and the distributor “un-brazed” from the system in order to replace the existing nozzle with one of appropriate size. This is a labor intensive process that can be expensive and costly.
The present invention overcomes these obstacles by providing a distributor where the effective nozzle size can be modulated over the range of nozzle sizes offered for a particular distributor. This eliminates the need to stock an entire range of individual nozzles. The present invention ensures that the nozzle size selection is not restricted to specific sizes. Rather, any effective size can be selected throughout the entire range. This allows further customization of the distributor to the application. The present invention allows for the adjustment of the nozzle size after the distributor has been installed (brazed) and while the system is running. This reduces the cost since the installation time is eliminating, a greater efficiency is established, and the cooling capacity is optimized.